Processes for the preparation of 0-(2-aminobenzo[d]oxazol-5-yl)methyl hydroxylamine for the synthesis of 6,11-bicyclic erythromycin derivative EDP-182

ABSTRACT

The present invention relates to processes and intermediates for the preparation of 6-11 bicyclic erythromycin derivative known as EDP-182 (IX-a). In particular, the present invention relates to processes and intermediates for the preparation of O-(2-aminobenzo[d]oxazol-5-yl)methyl hydroxylamine:

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/778,203, filed on Mar. 2, 2006. The entire teachings of the aboveapplication are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to processes and intermediates useful inthe preparation of bridged erythromycin derivative known as EDP-182 andtheir respective pharmaceutically acceptable salts.

BACKGROUND OF THE INVENTION

Macrolide antibiotics play a therapeutically important role,particularly with the emergence of new pathogens. Structural differencesare related to the size of the lactone ring and to the number and nature(neutral or basic) of the sugars. Macrolides are classified according tothe size of the lactone ring (12, 14, 15 or 16 atoms). The macrolideantibiotic family (14-, 15- and 16-membered ring derivatives) shows awide range of characteristics (antibacterial spectrum, side-effects andbioavailability). Among the commonly used macrolides are erythromycin,clarithromycin, and azithromycin. Macrolides possessing a 3-oxo moietyin place of the 3-cladinose sugar are known as ketolides and have shownenhanced activity towards gram-negative bacteria and macrolide resistantgram-positive bacteria. The search for macrolide compounds which areactive against MLS_(B)-resistant strains(MLS_(B)=Macrolides-Lincosamides-type B Streptogramines) has become amajor goal, together with retaining the overall profile of themacrolides in terms of stability, tolerance and pharmacokinetics.

SUMMARY OF THE INVENTION

The present invention provides methods for preparing 6,11-bridgedmacrocyclic derivative known as EDP-182. Particularly, the presentinvention provides methods for preparingO-(2-aminobenzo[d]oxazol-5-yl)methyl hydroxylamine as the keyintermediate for the preparation of EDP-182.

DETAILED DESCRIPTION OF THE INVENTION

The processes of the present invention are suitable for synthesizing6-11 bicyclic erythromycin derivative known as EDP-182, orpharmaceutically acceptable salts thereof. In one embodiment, theprocess comprises the step of reacting a compound of formula (I):

or a pharmaceutically acceptable salt thereof with a compound of formulaII:

to produce a compound of formula III:

optionally in the presence of a palladium

catalyst,

wherein,

Each R₁ is independently selected from hydrogen, acyl, silane, asubstituted or unsubstituted, saturated or unsaturated aliphatic group,a substituted or unsubstituted, saturated or unsaturated alicyclicgroup, a substituted or unsubstituted aromatic group, a substituted orunsubstituted heteroaromatic group, saturated or unsaturatedheterocyclic group;

Q is independently selected from R₁, OR₁, or OC(O)R₁;

Z is selected from R₁, OR₁, OC(O)R₁, OC(O)NR₃R₄, OS(O)_(n)R₁, and

one of J or G is hydrogen and the other is selected from R₁, OR₁, orNR₃R₄;

or, J and G, taken together with the carbon atom to which they areattached, are selected from C═O, C═NR₁, C═NOR₁, C═NO(CH₂)_(m)R₁,C═NNHR₁, C═NNHCOR₁, C═NNHCONR₃R₄, C═NNHS(O)_(n)R₁, or C═N—N═CHR₁;

R_(p) is a hydroxyl protecting group;

m is an integer; and

n is 0, 1, or 2.

Preferred embodiments of the compound of Formula I are the compounds ofFormulas I-a and I-b:

In a most preferred embodiment, the compound of Formula I is a compoundof formula (I-c):

Although compounds of formula I are preferred, other macrocycliccompounds which contain two or more nucleophilic moieties (e.g. —OH,—NH₂, —NH—, etc.) may be substituted for the starting material offormula I.

Preferred embodiments of the compound of formula II are compoundswherein R₁ is tert-butyl.

Compounds of formula (II) that are useful in the preparation ofcompounds of formula (III), are prepared by the process comprising thestep of reacting a compound of formula (II-a):

with a C₁-C₆ alkyl anhydride in the presence of a phase transfercatalyst.

A most preferred embodiment of the compound of Formula III is thecompound of Formula III-a:

Another embodiment of the present invention, therefore, is a processcomprising the step of hydrolyzing a compound of formula (III) withaqueous acid to provide a compound of formula (IV).

A most preferred embodiment of the compound of formula (IV) is acompound of formula (IV-a):

Yet a further embodiment of the present invention, therefore, is aprocess comprising the step of reducing a compound of formula (IV) witha reducing agent to provide a compound of formula (V):

Preferred embodiments of the compound of formula (V) are compounds offormula (V-a):

Yet another embodiment of the present invention, therefore, is a processcomprising the step of acylating a compound of formula (V) with anacylating agent to provide a compound of formula (VI):

Preferred embodiments the compound of formula (VI) are compounds offormula (VI-a):

Yet a further embodiment of the present invention, therefore, is aprocess comprising the step of oxidatively cleaving a compound offormula (VI) with a cleaving reagent or reagents which are capable ofperforming oxidative cleavage to provide a compound of formula (VII):

Preferred embodiments of the compound of formula (VII) are compounds offormulas (VII-a):

Yet another embodiment of the present invention, therefore, is a processwhich comprises the step of oxidizing a compound of formula (VII) withan oxidizing agent or agents to provide a compound of formula (VIII):

The most preferred embodiments of the compound of formula (VIII) arecompounds of formula (VIII-a):

Compounds of formula (VIII) are useful as intermediates in the synthesisof compounds of formula (IX):

A most preferred embodiment of the compound of formula (IX) is acompound of formula (IX-a):

Another embodiment of the present invention is a process which comprisesthe step of reacting a compound of formula (VIII) with1-(2-aminobenzo[d]oxazol-5-yl)-hydroxylamine to provide a compound offormula (IX-a). In a most preferred embodiment of this process, acompound of formula (VIII-a) is treated with a1-(2-aminobenzo[d]oxazol-5-yl)-hydroxylamine (X):

to provide a compound of formula (IX-a).

The present invention provides a process for the preparation ofcompounds of formula (XI);

Wherein R₃ and R₄ are hydrogen;

or one of R₃ or R₄ is a hydrogen and the other is selected from:

-   -   (a) C(O)R₅, where R₅ is C₁-C₆ alkyl, optionally substituted with        one or more substituents selected from aryl, substituted aryl,        heteroaryl, or substituted heteroaryl;    -   (b) C(O)OR₅, where R₅ is as previously defined; or    -   wherein A and B are each independently hydrogen, a substituted        or unsubstituted aliphatic group, a substituted or unsubstituted        cyclic group, a substituted or unsubstituted heterocyclic group,        a substituted or unsubstituted aryl group, a substituted or        unsubstituted alicyclic group, or a substituted or unsubstituted        heteroaryl group; or A and B taken together with the carbon to        which they are attached form a cyclic moiety selected from:        aryl, substituted aryl, heterocyclic, substituted heterocyclic,        alicyclic, or substituted alicyclic;

-   alternatively, R₃ and R₄ are taken together with the nitrogen atom    to which they are attached to form N═C(R₆)(R₇), where R₆ and R₇ are    each independently selected from a substituted or unsubstituted    aliphatic group, a substituted or unsubstituted cyclic group, a    substituted or unsubstituted heterocyclic group, a substituted or    unsubstituted aryl group, a substituted or unsubstituted alicyclic    group, or a substituted or unsubstituted heteroaryl group    said process comprising:    -   (1) reducing 4-(hydroxymethyl)-2-nitrophenol with a reducing        agent to provide compound of formula (XII):

-   -   (2) reacting cyanogenbromide with compound of formula (XII) in a        solvent to give compound of formula (XIII):

-   -   (3) halogenating the resulting compound with a chlorinating        reagent to provide a compound of formula (XIV);

-   -   (4) treating compound of formula (XIV) with compounds of formula        R₃R₄NOH wherein R₃ and R₄ are as previously defined, in the        presence of base to yield compounds of formula (XI).

Yet another embodiment, the process further comprising the step ofhydrolyzing the compound of formula XI with a base or an acid in aprotogenic organic solvent or aqueous solution, to yield1-(2-aminobenzo[d]oxazol-5-yl)-hydroxylamine (X):

In another embodiment, the process for the synthesis of a compound offormula (XV):

wherein R₃ and R₄ are previously defined and the said processcomprising:

-   -   (1) reacting cyanogenbromide with 2-amino-4-methylphenol in a        solvent to give compound of formula (XVI):

-   -   (2) protecting the compound of formula (XVI) with succinic        anhydride to yield compound of formula (VI):

-   -   (3) brominating the compound of formula (XVII) with a        brominating reagent to give compound of the following formula        (XVIII):

-   -   (4) treating the compound of formula (XVIII) with a compound of        formula R₃R₄NOH in the presence of base, to provide a compound        of formula (XV).

Yet in another embodiment, the process further comprising the step ofdeprotecting the compound of formula (XIX) with a base or an acid in aprotogenic organic solvent or aqueous solution, to yield1-(2-aminobenzo[d]oxazol-5-yl)-hydroxylamine (X).

Definitions

Listed below are definitions of various terms used to describe thisinvention. These definitions apply to the terms as they are usedthroughout this specification and claims, unless otherwise limited inspecific instances, either individually or as part of a larger group.

An “aliphatic group” is non-aromatic moiety that may contain anycombination of carbon atoms, hydrogen atoms, halogen atoms, oxygen,nitrogen or other atoms, and optionally contain one or more units ofunsaturation, e.g., double and/or triple bonds. An aliphatic group maybe straight chained, branched or cyclic and preferably contains betweenabout 1 and about 24 carbon atoms, more typically between about 1 andabout 12 carbon atoms. In addition to aliphatic hydrocarbon groups,aliphatic groups include, for example, polyalkoxyalkyls, such aspolyalkylene glycols, polyamines, and polyimines, for example. Suchaliphatic groups may be further substituted.

Suitable aliphatic or aromatic substituents include, but are not limitedto, —F, —Cl, —Br, —I, —OH, protected hydroxy, aliphatic ethers, aromaticethers, oxo, —NO₂, —CN, —C₁-C₁₂-alkyl optionally substituted withhalogen (such as perhaloalkyls), C₂-C₁₂-alkenyl optionally substitutedwith halogen, —C₂-C₁₂-alkynyl optionally substituted with halogen, —NH₂,protected amino, —NH—C₁-C₁₂-alkyl, —NH—C₂-C₁₂-alkenyl,—NH—C₂-C₁₂-alkenyl, —NH—C₃-C₁₂-cycloalkyl, —NH-aryl, —NH-heteroaryl,—NH-heterocycloalkyl, -dialkylamino, -diarylamino, -diheteroarylamino,—O—C₁-C₁₂-alkyl, —O—C₂-C₁₂-alkenyl, —O—C₂-C₁₂-alkynyl,—O—C₃-C₁₂-cycloalkyl, —O—aryl, —O-heteroaryl, —O-heterocycloalkyl,—C(O)—C₁-C₁₂-alkyl, —C(O)—C₂-C₁₂-alkenyl, —C(O)—C₂-C₁₂-alkynyl,—C(O)—C₃-C₁₂-cycloalkyl, —C(O)-aryl, —C(O)-heteroaryl,—C(O)-heterocycloalkyl, —CONH₂, —CONH—C₁-C₁₂-alkyl,—CONH—C₂-C₁₂-alkenyl, —CONH—C₂-C₁₂-alkynyl, —CONH—C₃-C₁₂-cycloalkyl,—CONH-aryl, —CONH-heteroaryl, —CONH-heterocycloalkyl, —CO₂—C₁-C₁₂-alkyl,—CO₂—C₂-C₁₂-alkenyl, —CO₂—C₂-C₁₂-alkynyl, —CO₂—C₃-C₁₂-cycloalkyl,—CO₂-aryl, —CO₂-heteroaryl, —CO₂-heterocycloalkyl, —OCO₂—C₁-C₁₂-alkyl,—OCO₂—C₂-C₁₂-alkenyl, —OCO₂—C₂-C₁₂-alkynyl, —OCO₂—C₃-C₁₂-cycloalkyl,—OCO₂-aryl, —OCO₂-heteroaryl, —OCO₂-heterocycloalkyl, —OCONH₂,—OCONH—C₁-C₁₂-alkyl, —OCONH—C₂-C₁₂-alkenyl, —OCONH—C₂-C₁₂-alkynyl,—OCONH—C₃-C₁₂-cycloalkyl, —OCONH-aryl, —OCONH-heteroaryl,—OCONH-heterocycloalkyl, —NHC(O)—C₁-C₁₂-alkyl, —NHC(O)—C₂-C₁₂-alkenyl,—NHC(O)—C₂-C₁₂-alkynyl, —NHC(O)—C₃-C₁₂-cycloalkyl, —NHC(O)-aryl,—NHC(O)-heteroaryl, —NHC(O)-heterocycloalkyl, —NHCO₂—C₁-C₁₂-alkyl,—NHCO₂—C₂-C₁₂-alkenyl, —NHCO₂—C₂-C₁₂-alkynyl, —NHCO₂—C₃-C₁₂-cycloalkyl,—NHCO₂-aryl, —NHCO₂-heteroaryl, —NHCO₂-heterocycloalkyl, —NHC(O)NH₂,NHC(O)NH—C₁-C₁₂-alkyl, —NHC(O)NH—C₂-C₁₂-alkenyl,—NHC(O)NH—C₂-C₁₂-alkynyl, —NHC(O)NH—C₃-C₁₂-cycloalkyl, —NHC(O)NH-aryl,—NHC(O)NH-heteroaryl, —NHC(O)NH-heterocycloalkyl, NHC(S)NH₂,NHC(S)NH—C₁-C₁₂-alkyl, —NHC(S)NH—C₂-C₁₂-alkenyl,—NHC(S)NH—C₂-C₁₂-alkynyl, —NHC(S)NH—C₃-C₁₂-cycloalkyl, —NHC(S)NH-aryl,—NHC(S)NH-heteroaryl, —NHC(S)NH-heterocycloalkyl, —NHC(NH)NH₂,NHC(NH)NH—C₁-C₁₂-alkyl, —NHC(NH)NH—C₂-C₁₂-alkenyl,—NHC(NH)NH—C₂-C₁₂-alkynyl, —NHC(NH)NH—C₃-C₁₂-cycloalkyl,—NHC(NH)NH-aryl, —NHC(NH)NH-heteroaryl, —NHC(NH)NH-heterocycloalkyl,NHC(NH)—C₁-C₁₂-alkyl, —NHC(NH)—C₂-C₁₂-alkenyl, —NHC(H)—C₂-C₁₂-alkynyl,—NHC(NH)—C₃-C₁₂-cycloalkyl, —NHC(NH)-aryl, —NHC(NH)-heteroaryl,—NHC(NH)-heterocycloalkyl, —C(NH)NH—C₁-C₁₂-alkyl,—C(NH)NH—C₂-C₁₂-alkenyl, —C(NH)NH—C₂-C₁₂-alkynyl,—C(NH)NH—C₃-C₁₂-cycloalkyl, —C(NH)NH-aryl, —C(NH)NH-heteroaryl,—C(NH)NH-heterocycloalkyl, —S(O)—C₁-C₁₂-alkyl, —S(O)—C₂-C₁₂-alkenyl,—S(O)—C₂-C₁₂-alkynyl, —S(O)—C₃-C₁₂-cycloalkyl, —S(O)-aryl,—S(O)-heteroaryl, —S(O)-heterocycloalkyl —SO₂NH₂, —SO₂NH—C₁-C₁₂-alkyl,—SO₂NH—C₂-C₁₂-alkenyl, —SO₂NH—C₂-C₁₂-alkynyl, —SO₂NH—C₃-C₁₂-cycloalkyl,—SO₂NH-aryl, —SO₂NH-heteroaryl, —SO₂NH-heterocycloalkyl,—NHSO₂—C₁-C₁₂-alkyl, —NHSO₂—C₂-C₁₂-alkenyl, —NHSO₂—C₂-C₁₂-alkynyl,—NHSO₂—C₃-C₁₂-cycloalkyl, —NHSO₂-aryl, —NHSO₂-heteroaryl,—NHSO₂-heterocycloalkyl, —CH₂NH₂, —CH₂SO₂CH₃, -aryl, -arylalkyl,-heteroaryl, -heteroarylalkyl, -heterocycloalkyl, —C₃-C₁₂-cycloalkyl,polyalkoxyalkyl, polyalkoxy, -methoxymethoxy, -methoxyethoxy, —SH,—S—C₁-C₁₂-alkyl, —S—C₂-C₁₂-alkenyl, —S—C₂-C₁₂-alkynyl,—S—C₃-C₁₂-cycloalkyl, —S-aryl, —S-heteroaryl, —S-heterocycloalkyl, ormethylthiomethyl. It is understood that the aryls, heteroaryls, alkylsand the like can be further substituted.

The terms “C₂-C₁₂ alkenyl” or “C₂-C₆ alkenyl,” as used herein, denote amonovalent group derived from a hydrocarbon moiety containing from twoto twelve or two to six carbon atoms having at least one carbon-carbondouble bond by the removal of a single hydrogen atom. Alkenyl groupsinclude, but are not limited to, for example, ethenyl, propenyl,butenyl, 1-methyl-2-buten-1-yl, alkadienes and the like.

The term “substituted alkenyl,” as used herein, refers to a “C₂-C₁₂alkenyl” or “C₂-C₆ alkenyl” group as previously defined, substituted byone, two, three or more aliphatic substituents.

The terms “C₂-C₁₂ alkynyl” or “C₂-C₆ alkynyl,” as used herein, denote amonovalent group derived from a hydrocarbon moiety containing from twoto twelve or two to six carbon atoms having at least one carbon-carbontriple bond by the removal of a single hydrogen atom. Representativealkynyl groups include, but are not limited to, for example, ethynyl,1-propynyl, 1-butynyl, and the like.

The term “substituted alkynyl,” as used herein, refers to a “C₂-C₁₂alkynyl” or “C₂-C₆ alkynyl” group as previously defined, substituted byone, two, three or more aliphatic substituents.

The term “C₁-C₆ alkoxy,” as used herein, refers to a C₁-C₆ alkyl group,as previously defined, attached to the parent molecular moiety throughan oxygen atom. Examples of C₁-C₆-alkoxy include, but are not limitedto, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, sec-butoxy,tert-butoxy, n-pentoxy, neopentoxy and n-hexoxy.

The terms “halo” and “halogen,” as used herein, refer to an atomselected from fluorine, chlorine, bromine and iodine.

The terms “aryl” or “aromatic” as used herein, refer to a mono- orbicyclic carbocyclic ring system having one or two aromatic ringsincluding, but not limited to, phenyl, naphthyl, tetrahydronaphthyl,indanyl, idenyl and the like.

The terms “substituted aryl” or “substituted aromatic,” as used herein,refer to an aryl or aromatic group substituted by one, two, three ormore aromatic substituents.

The term “arylalkyl,” as used herein, refers to an aryl group attachedto the parent compound via a C₁-C₃ alkyl or C₁-C₆ alkyl residue.Examples include, but are not limited to, benzyl, phenethyl and thelike.

The term “substituted arylalkyl,” as used herein, refers to an arylalkylgroup, as previously defined, substituted by one, two, three or morearomatic substituents.

The terms “heteroaryl” or “heteroaromatic,” as used herein, refer to amono-, bi-, or tri-cyclic aromatic radical or ring having from five toten ring atoms of which at least one ring atom is selected from S, O andN; zero, one or two ring atoms are additional heteroatoms independentlyselected from S, O and N; and the remaining ring atoms are carbon,wherein any N or S contained within the ring may be optionally oxidized.Heteroaryl includes, but is not limited to, pyridinyl, pyrazinyl,pyrimidinyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl,isooxazolyl, thiadiazolyl, oxadiazolyl, thiophenyl, furanyl, quinolinyl,isoquinolinyl, benzimidazolyl, benzooxazolyl, quinoxalinyl, and thelike. The heteroaromatic ring may be bonded to the chemical structurethrough a carbon or hetero atom.

The terms “substituted heteroaryl” or “substituted heteroaromatic,” asused herein, refer to a heteroaryl or heteroaromatic group, substitutedby one, two, three, or more aromatic substituents.

The term “alicyclic,” as used herein, denotes a monovalent group derivedfrom a monocyclic or bicyclic saturated carbocyclic ring compound by theremoval of a single hydrogen atom. Examples include, but not limited to,cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, bicyclo[2.2.1]heptyl,and bicyclo[2.2.2]octyl.

The term “substituted alicyclic,” as used herein, refers to an alicyclicgroup substituted by one, two, three or more aliphatic substituents.

The term “heterocyclic,” as used herein, refers to a non-aromatic 5-, 6-or 7-membered ring or a bi- or tri-cyclic group fused system, where (i)each ring contains between one and three heteroatoms independentlyselected from oxygen, sulfur and nitrogen, (ii) each 5-membered ring has0 to 1 double bonds and each 6-membered ring has 0 to 2 double bonds,(iii) the nitrogen and sulfur heteroatoms may optionally be oxidized,(iv) the nitrogen heteroatom may optionally be quatemized, (iv) any ofthe above rings may be fused to a benzene ring, and (v) the remainingring atoms are carbon atoms which may be optionally oxo-substituted.Representative heterocycloalkyl groups include, but are not limited to,[1,3]dioxolane, pyrrolidinyl, pyrazolinyl, pyrazolidinyl, imidazolinyl,imidazolidinyl, piperidinyl, piperazinyl, oxazolidinyl, isoxazolidinyl,morpholinyl, thiazolidinyl, isothiazolidinyl, quinoxalinyl,pyridazinonyl, and tetrahydrofuryl.

The term “substituted heterocyclic,” as used herein, refers to aheterocyclic group, as previously defined, substituted by one, two,three or more aliphatic substituents.

The term “heteroarylalkyl,” as used herein, to an heteroaryl groupattached to the parent compound via a C₁-C₃ alkyl or C₁-C₆ alkylresidue. Examples include, but are not limited to, pyridinylmethyl,pyrimidinylethyl and the like.

The term “substituted heteroarylalkyl,” as used herein, refers to aheteroarylalkyl group, as previously defined, substituted by independentreplacement of one, two, or three or more aromatic substituents.

The term “alkylamino” refers to a group having the structure —NH(C₁-C₁₂alkyl).

The term “dialkylamino” refers to a group having the structure —N(C₁-C₁₂alkyl) (C₁-C₁₂ alkyl), where C₁-C₁₂ alkyl is as previously defined.Examples of dialkylamino are, but not limited to, dimethylamino,diethylamino, methylethylamino, piperidino, and the like.

The term “alkoxycarbonyl” represents an ester group, i.e., an alkoxygroup, attached to the parent molecular moiety through a carbonyl groupsuch as methoxycarbonyl, ethoxycarbonyl, and the like.

The term “carboxaldehyde,” as used herein, refers to a group of formula—CHO.

The term “carboxy,” as used herein, refers to a group of formula —COOH.

The term “carboxamide,” as used herein, refers to a group of formula—C(O)NH(C₁-C₁₂ alkyl) or —C(O)N(C₁-C₁₂ alkyl) (C₁-C₁₂ alkyl), —C(O)NH₂,NHC(O)(C₁-C₁₂ alkyl), N(C₁-C₁₂ alkyl)C(O)(C₁-C₁₂ alkyl) and the like.

The term “hydroxy protecting group,” as used herein, refers to a labilechemical moiety which is known in the art to protect a hydroxyl groupagainst undesired reactions during synthetic procedures. After saidsynthetic procedure(s) the hydroxy protecting group as described hereinmay be selectively removed. Hydroxy protecting groups as known in theare described generally in T. H. Greene and P. G. M. Wuts, ProtectiveGroups in Organic Synthesis, 3rd edition, John Wiley & Sons, New York(1999). Examples of hydroxyl protecting groups includebenzyloxycarbonyl, 4-nitrobenzyloxycarbonyl, 4-bromobenzyloxycarbonyl,4-methoxybenzyloxycarbonyl, methoxycarbonyl, tert-butoxycarbonyl,isopropoxycarbonyl, diphenylmethoxycarbonyl,2,2,2-trichloroethoxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl,2-furfuryloxycarbonyl, allyloxycarbonyl, acetyl, formyl, chloroacetyl,trifluoroacetyl, methoxyacetyl, phenoxyacetyl, benzoyl, methyl, t-butyl,2,2,2-trichloroethyl, 2-trimethylsilyl ethyl, 1,1-dimethyl-2-propenyl,3-methyl-3-butenyl, allyl, benzyl, para-methoxybenzyldiphenylmethyl,triphenylmethyl(trityl), tetrahydrofuryl, methoxymethyl,methylthiomethyl, benzyloxymethyl, 2,2,2-triehloroethoxymethyl,2-(trimethylsilyl)ethoxymethyl, methanesulfonyl, para-toluenesulfonyl,trimethylsilyl, triethylsilyl, triisopropylsilyl, and the like.Preferred hydroxyl protecting groups for the present invention areacetyl (Ac or —C(O)CH₃), benzoyl (Bz or —C(O)C₆H₅), and trimethylsilyl(TMS or —Si(CH₃)₃).

The term “protected hydroxy,” as used herein, refers to a hydroxy groupprotected with a hydroxy protecting group, as defined above, includingbenzyloxycarbonyl, 4-nitrobenzyloxycarbonyl, 4-bromobenzyloxycarbonyl,4-methoxybenzyloxycarbonyl, methoxycarbonyl, tert-butoxycarbonyl,isopropoxycarbonyl, diphenylmethoxycarbonyl,2,2,2-trichloroethoxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl,2-furfuryloxycarbonyl, allyloxycarbonyl, acetyl, formyl, chloroacetyl,trifluoroacetyl, methoxyacetyl, phenoxyacetyl, benzoyl, methyl, t-butyl,2,2,2-trichloroethyl, 2-trimethylsilyl ethyl, 1,1-dimethyl-2-propenyl,3-methyl-3-butenyl, allyl, benzyl, para-methoxybenzyldiphenylmethyl,triphenylmethyl(trityl), tetrahydrofuryl, methoxymethyl,methylthiomethyl, benzyloxymethyl, 2,2,2-triehloroethoxymethyl,2-(trimethylsilyl)ethoxymethyl, methanesulfonyl, para-toluenesulfonyl,trimethylsilyl, triethylsilyl, triisopropylsilyl, and the like.Preferred hydroxyl protecting groups for the present invention areacetyl (Ac or —C(O)CH₃), benzoyl (Bz or —C(O)C₆H₅), and trimethylsilyl(TMS or —Si(CH₃)₃).

The term “amino protecting group,” as used herein, refers to a labilechemical moiety which is known in the art to protect an amino groupagainst undesired reactions during synthetic procedures. After saidsynthetic procedure(s) the amino protecting group as described hereinmay be selectively removed. Amino protecting groups as known in the aredescribed generally in T. H. Greene and P. G. M. Wuts, Protective Groupsin Organic Synthesis, 3rd edition, John Wiley & Sons, New York (1999).Examples of amino protecting groups include, but are not limited to,t-butoxycarbonyl, 9-fluorenylmethoxycarbonyl, benzyloxycarbonyl, and thelike.

The term “protected amino,” as used herein, refers to an amino groupprotected with an amino protecting group as defined above.

The term “acy” includes residues derived from acids, including but notlimited to carboxylic acids, carbamic acids, carbonic acids, sulfonicacids, and phosphorous acids. Examples include aliphatic carbonyls,aromatic carbonyls, aliphatic sulfonyls, aromatic sulfinyls, aliphaticsulfinyls, aromatic phosphates and aliphatic phosphates.

The term “aprotic solvent,” as used herein, refers to a solvent that isrelatively inert to proton activity, i.e., not acting as a proton-donor.Examples include, but are not limited to, hydrocarbons, such as hexaneand toluene, for example, halogenated hydrocarbons, such as, forexample, methylene chloride, ethylene chloride, chloroform, and thelike, heterocyclic compounds, such as, for example, tetrahydrofuran andN-methylpyrrolidinone, and ethers such as diethyl ether,bis-methoxymethyl ether. Such compounds are well known to those skilledin the art, and it will be obvious to those skilled in the art thatindividual solvents or mixtures thereof may be preferred for specificcompounds and reaction conditions, depending upon such factors as thesolubility of reagents, reactivity of reagents and preferred temperatureranges, for example. Further discussions of aprotic solvents may befound in organic chemistry textbooks or in specialized monographs, forexample: Organic Solvents Physical Properties and Methods ofPurification, 4th ed., edited by John A. Riddick et al., Vol. II, in theTechniques of Chemistry Series, John Wiley & Sons, NY, 1986.

The term “protogenic organic solvent,” as used herein, refers to asolvent that tends to provide protons, such as an alcohol, for example,methanol, ethanol, propanol, isopropanol, butanol, t-butanol, and thelike. Such solvents are well known to those skilled in the art, and itwill be obvious to those skilled in the art that individual solvents ormixtures thereof may be preferred for specific compounds and reactionconditions, depending upon such factors as the solubility of reagents,reactivity of reagents and preferred temperature ranges, for example.Further discussions of protogenic solvents may be found in organicchemistry textbooks or in specialized monographs, for example: OrganicSolvents Physical Properties and Methods of Purification, 4th ed.,edited by John A. Riddick et al., Vol. II, in the Techniques ofChemistry Series, John Wiley & Sons, NY, 1986.

The term “oxidizing agent(s),” as used herein, refers to reagents usefulfor oxidizing the 3-hydroxyl of the macrolide ring to the 3-carbonyl.Oxidizing agents suitable in the present process are either Swemoxidation reagents (dimethyl sulfoxide and an electrophilic compoundselected from dicyclohexylcarbodiimide, acetic anhydride,trifluoroacetic anhydride, oxalyl chloride, or sulfur trioxide), DessMartin oxidation reagents, or Corey-Kim oxidation reagents. A preferredmethod of oxidation is the use of the Corey-Kim oxidation reagentsN-chlorosuccinimide-dimethyl sulfide complex.

The term “palladium catalyst,” as used herein, refers to optionallysupported palladium(0) such as palladium metal, palladium on carbon,palladium on acidic, basic, or neutral alumina, and the like;palladium(0) complexes such as tetrakis(triphenylphosphine)palladium(0)tris(dibenzylideneacetone)dipalladium(0); palladium(II) salts such aspalladium acetate or palladium chloride; and palladium(II) complexessuch as allylpalladium(II) chloride dimer,(1,1′-bis(diphenylphosphino)ferrocene)-dichloropalladium(II),bis(acetato)bis(triphenylphosphine)palladium(II), andbis(acetonitrile)dichloropalladium(II).

Combinations of substituents and variables envisioned by this inventionare only those that result in the formation of stable compounds. Theterm “stable”, as used herein, refers to compounds which possessstability sufficient to allow manufacture and which maintains theintegrity of the compound for a sufficient period of time to be usefulfor the purposes detailed herein.

The synthesized compounds can be separated from a reaction mixture andfurther purified by a method such as column chromatography, highpressure liquid chromatography, or recrystallization. As can beappreciated by the skilled artisan, further methods of synthesizing thecompounds of the formulae herein will be evident to those of ordinaryskill in the art. Additionally, the various synthetic steps may beperformed in an alternate sequence or order to give the desiredcompounds. Synthetic chemistry transformations and protecting groupmethodologies (protection and deprotection) useful in synthesizing thecompounds described herein are known in the art and include, forexample, those such as described in R. Larock, Comprehensive OrganicTransformations, VCH Publishers (1989); T. W. Greene and P. G. M. Wuts,Protective Groups in Organic Synthesis, 2d. Ed., John Wiley and Sons(1991); L. Fieser and M. Fieser, Fieser and Fieser's Reagents forOrganic Synthesis, John Wiley and Sons (1994); and L. Paquette, ed.,Encyclopedia of Reagents for Organic Synthesis, John Wiley and Sons(1995).

The compounds of this invention may be modified by appending appropriatefunctionalities to enhance selective biological properties. Suchmodifications are known in the art and may include those which increasebiological penetration into a given biological system (e.g., blood,lymphatic system, central nervous system), increase oral availability,increase solubility to allow administration by injection, altermetabolism and alter rate of excretion.

The compounds described herein contain one or more asymmetric centersand thus give rise to enantiomers, diastereomers, and otherstereoisomeric forms that may be defined, in terms of absolutestereochemistry, as (R)- or (S)-, or as (D)- or (L)- for amino acids.The present invention is meant to include all such possible isomers, aswell as their racemic and optically pure forms. Optical isomers may beprepared from their respective optically active precursors by theprocedures described above, or by resolving the racemic mixtures. Theresolution can be carried out in the presence of a resolving agent, bychromatography or by repeated crystallization or by some combination ofthese techniques which are known to those skilled in the art. Furtherdetails regarding resolutions can be found in Jacques, et al.,Enantiomers Racemates and Resolutions (John Wiley & Sons, 1981). Whenthe compounds described herein contain olefinic double bonds, otherunsaturation, or other centers of geometric asymmetry, and unlessspecified otherwise, it is intended that the compounds include both Eand Z geometric isomers or cis- and trans- isomers. Likewise, alltautomeric forms are also intended to be included. The configuration ofany carbon-carbon double bond appearing herein is selected forconvenience only and is not intended to designate a particularconfiguration unless the text so states; thus a carbon-carbon doublebond or carbon-heteroatom double bond depicted arbitrarily herein astrans may be cis, trans, or a mixture of the two in any proportion.

As used herein, the term “pharmaceutically acceptable salt” refers tothose salts which are, within the scope of sound medical judgment,suitable for use in contact with the tissues of humans and lower animalswithout undue toxicity, irritation, allergic response and the like, andare commensurate with a reasonable benefit/risk ratio. Pharmaceuticallyacceptable salts are well known in the art. For example, S. M. Berge, etal. describes pharmaceutically acceptable salts in detail in J.Pharmaceutical Sciences, 66: 1-19 (1977). The salts can be prepared insitu during the final isolation and purification of the compounds of theinvention, or separately by reacting the free base function with asuitable organic acid. Examples of pharmaceutically acceptable include,but are not limited to, nontoxic acid addition salts are salts of anamino group formed with inorganic acids such as hydrochloric acid,hydrobromic acid, phosphoric acid, sulfuric acid and perchloric acid orwith organic acids such as acetic acid, maleic acid, tartaric acid,citric acid, succinic acid or malonic acid or by using other methodsused in the art such as ion exchange. Other pharmaceutically acceptablesalts include, but are not limited to, adipate, alginate, ascorbate,aspartate, benzenesulfonate, benzoate, bisulfate, borate, butyrate,camphorate, camphorsulfonate, citrate, cyclopentanepropionate,digluconate, dodecylsulfate, ethanesulfonate, formate, fumarate,glucoheptonate, glycerophosphate, gluconate, hemisulfate, heptanoate,hexanoate, hydroiodide, 2-hydroxy-ethanesulfonate, lactobionate,lactate, laurate, lauryl sulfate, malate, maleate, malonate,methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oleate,oxalate, palmitate, pamoate, pectinate, persulfate, 3-phenylpropionate,phosphate, picrate, pivalate, propionate, stearate, succinate, sulfate,tartrate, thiocyanate, p-toluenesulfonate, undecanoate, valerate salts,and the like. Representative alkali or alkaline earth metal saltsinclude sodium, lithium, potassium, calcium, magnesium, and the like.Further pharmaceutically acceptable salts include, when appropriate,nontoxic ammonium, quaternary ammonium, and amine cations formed usingcounterions such as halide, hydroxide, carboxylate, sulfate, phosphate,nitrate, alkyl having from 1 to 6 carbon atoms, sulfonate and arylsulfonate.

As used herein, the term “pharmaceutically acceptable ester” refers toesters which hydrolyze in vivo and include those that break down readilyin the human body to leave the parent compound or a salt thereof.Suitable ester groups include, for example, those derived frompharmaceutically acceptable aliphatic carboxylic acids, particularlyalkanoic, alkenoic, cycloalkanoic and alkanedioic acids, in which eachalkyl or alkenyl moiety advantageously has not more than 6 carbon atoms.Examples of particular esters include, but are not limited to, formates,acetates, propionates, butyrates, acrylates and ethylsuccinates.

The term “pharmaceutically acceptable prodrugs” as used herein refers tothose prodrugs of the compounds of the present invention which are,within the scope of sound medical judgment, suitable for use in contactwith the tissues of humans and lower animals with undue toxicity,irritation, allergic response, and the like, commensurate with areasonable benefit/risk ratio, and effective for their intended use, aswell as the zwitterionic forms, where possible, of the compounds of thepresent invention. “Prodrug”, as used herein means a compound which isconvertible in vivo by metabolic means (e.g. by hydrolysis) to acompound of Formula I. Various forms of prodrugs are known in the art,for example, as discussed in Bundgaard, (ed.), Design of Prodrugs,Elsevier (1985); Widder, et al. (ed.), Methods in Enzymology, vol. 4,Academic Press (1985); Krogsgaard-Larsen, et al., (ed). “Design andApplication of Prodrugs, Textbook of Drug Design and Development,Chapter 5, 113-191 (1991); Bundgaard, et al., Journal of Drug DeliverReviews, 8:1-38(1992); Bundgaard, J. of Pharmaceutical Sciences, 77:285et seq. (1988); Higuchi and Stella (eds.) Prodrugs as Novel DrugDelivery Systems, American Chemical Society (1975); and Bernard Testa &Joachim Mayer, “Hydrolysis In Drug And Prodrug Metabolism: Chemistry,Biochemistry And Enzymology,” John Wiley and Sons, Ltd. (2002).

This invention also encompasses pharmaceutical compositions containing,and methods of treating bacterial infections through administering,pharmaceutically acceptable prodrugs of compounds of the formula I. Forexample, compounds of formula I having free amino, amido, hydroxy orcarboxylic groups can be converted into prodrugs. Prodrugs includecompounds wherein an amino acid residue, or a polypeptide chain of twoor more (e.g., two, three or four) amino acid residues is covalentlyjoined through an amide or ester bond to a free amino, hydroxy orcarboxylic acid group of compounds of formula I. The amino acid residuesinclude but are not limited to the 20 naturally occurring amino acidscommonly designated by three letter symbols and also includes4-hydroxyproline, hydroxylysine, demosine, isodemosine,3-methylhistidine, norvalin, beta-alanine, gamma-aminobutyric acid,citrulline homocysteine, homoserine, ornithine and methionine sulfone.Additional types of prodrugs are also encompassed. For instance, freecarboxyl groups can be derivatized as amides or alkyl esters. Freehydroxy groups may be derivatized using groups including but not limitedto hemisuccinates, phosphate esters, dimethylaminoacetates, andphosphoryloxymethyloxycarbonyls, as outlined in Advanced Drug DeliveryReviews, 1996, 19, 115. Carbamate prodrugs of hydroxy and amino groupsare also included, as are carbonate prodrugs, sulfonate esters andsulfate esters of hydroxy groups. Derivatization of hydroxy groups as(acyloxy)methyl and (acyloxy)ethyl ethers wherein the acyl group may bean alkyl ester, optionally substituted with groups including but notlimited to ether, amine and carboxylic acid functionalities, or wherethe acyl group is an amino acid ester as described above, are alsoencompassed. Prodrugs of this type are described in J. Med. Chem. 1996,39, 10. Free amines can also be derivatized as amides, sulfonamides orphosphonamides. All of these prodrug moieties may incorporate groupsincluding but not limited to ether, amine and carboxylic acidfunctionalities.

Suitable concentrations of reactants is 0.01M to 10M, typically 0.1M to1M. Suitable temperatures include −10° C. to 250° C., typically −78° C.to 150° C., more typically −78° C. to 100° C., still more typically 0°C. to 100° C. Reaction vessels are preferably made of any material whichdoes not substantial interfere with the reaction. Examples includeglass, plastic, and metal. The pressure of the reaction canadvantageously be operated at atmospheric pressure. The atmospheresincludes, for example, air, for oxygen and water insensitive reactions,or nitrogen or argon, for oxygen or water sensitive reactions.

The term “in situ,” as used herein, refers to use of an intermediate inthe solvent or solvents in which the intermediate was prepared withoutremoval of the solvent.

Unless otherwise defined, all technical and scientific terms used hereinare accorded the meaning commonly known to one with ordinary skill inthe art. All publications, patents, published patent applications, andother references mentioned herein are hereby incorporated by referencein their entirety.

Abbreviations

Abbreviations which may be used in the descriptions of the scheme andthe examples that follow are:

Ac for acetyl;

AIBN for azobisisobutyronitrile;

Bu₃SnH for tributyltin hydride;

CDI for carbonyldiimidazole;

dba for dibenzylidene acetone;

dppb for diphenylphosphino butane or 1,4-bis(diphenylphosphino)butane;

DBU for 1,8-diazabicyclo[5.4.0]undec-7-ene;

DEAD for diethylazodicarboxylate;

DMAP for dimethylaminopyridine;

DMF for dimethyl formamide;

DPPA for diphenylphosphoryl azide;

EtOAc for ethyl acetate;

HPLC for high-pressure liquid chromatography;

MeOH for methanol;

NaN(TMS)₂ for sodium bis(trimethylsilyl)amide;

NMM for N-methylmorpholine;

NMMO for N-methylmorpholine N-oxide;

TEA for triethylamine;

THF for tetrahydrofuran;

TPP or PPh₃ for triphenylphosphine;

MOM for methoxymethyl;

Boc for t-butoxycarbonyl;

Bz for benzoyl;

Bn for benzyl;

Ph for phenyl;

POPd for dihydrogendichlorobis(di-tert-butylphosphinito-κP)palladate(II);

TBS for tert-butyl dimethylsilyl; or

TMS for trimethylsilyl.

All other abbreviations used herein, which are not specificallydelineated above, shall be accorded the meaning which one of ordinaryskill in the art would attach.

Synthetic Schemes

The present invention will be better understood in connection withSchemes 1-6. It will be readily apparent to one of ordinary skill in theart that the process of the present invention can be practiced bysubstitution of the appropriate reactants and that the order of thesteps themselves can be varied.

Erythromycins can be protected as 9-oximes of formula (I-a) as describedin U.S. Pat. Nos. 4,990,602; 4,331,803; 4,680,386; and 4,670,549.Reaction of erythromycin A with hydroxylamine and formic acid inmethanol provides a compound of formula (I) wherein Q is OH and Z is

which can be further derivatized without isolation. The preferred amountof hydroxylamine is about 7 to about 10 molar equivalents per molarequivalent of erythromycin A. From about 2 to about 5 molar equivalentsof formic acid are used for each molar equivalent of erythromycin A.

The 2′- and 4″-hydroxyl groups as well as the hydroxyl of the 9-oxime ofcompounds of formula (I-a) can be protected sequentially orsimultaneously by reaction with a suitable hydroxyl-protecting reagentin an aprotic solvent, optionally in the presence of catalytic amountsof base, such as DMAP and/or TEA, as described in U.S. Pat. No.5,892,008, to provide a compound of formula (I-b). Typicalhydroxyl-protecting reagents include acetylating agents and silylatingagents such as acetyl chloride, acetic anhydride, benzoyl chloride,benzoic anhydride, benzyl chloroformate, hexamethyldisilazane, andtrialkylsilyl chlorides. A preferred hydroxyl-protecting reagent of thepresent invention is acetic anhydride.

Compounds of formula II, useful in the preparation of compounds offormula III, are prepared by treating 2-methylene-1,3-propanediol withdi-tert-butyl dicarbonate in an aprotic solvent, in the presence of aphase transfer catalyst (PTC) and an aqueous base. PTCs suitable for thepresent process include, but are not limited to, tetrabutylammoniumbromide, tetrabutylammonium bromide, tetrabutylammonium chloride,tetrabutylammonium fluoride trihydrate, tetrabutylammonium hydrogensulfate, tetrabutylammonium iodide, tetrabutylammonium thiocyanate,tetrabutylammonium tetrafluoroborate, benzyltetrabutylammonium chloride,and the like; the preferred of which is tetrabutylammonium hydrogensulfate. In a preferred embodiment of the present conversion, theaprotic solvent is dichloromethane, the aqueous base is 4M to 8M NaOH.

As illustrated in Scheme 1, step A, erythromycin derivatives of formula(I-b) are converted in the present invention to compounds of formula(III-a) by the treatment of the former with compounds of formula (II):

preferably where R₁ is tert-butyl, isopropyl, or isobutyl. In apreferred embodiment, the conversion takes place in an aprotic solvent,at a temperature range of between 30° C. and 100° C., in the presence ofa palladium catalyst and an additive for a period of less than about 12hours.

Alkylation of a compound of formula (I-b) with a compound of formula(II) preferably takes place in the presence of a palladium catalyst.Most palladium(0) catalysts are expected be effective in this process.Some palladium(II) catalysts, such as palladium(II) acetate, which areconverted into a palladium(0) species in-situ by a phosphine, will beeffective as well. See, for example, Beller et al. Angew. Chem. Int. Ed.Engl., 1995, 34 (17), 1848. A suitable palladium catalyst for thisreaction includes, but is not limited to, palladium(II) acetate,tetrakis(triphenylphospine)palladium(0),tris(dibenzylideneacetone)dipalladium(0) (Pd₂(dba)₃),tetradi(benzylideneacetone)dipalladium and the like. Palladium on carbonand palladium(II) halide catalysts are less preferred than otherpalladium catalysts for this process. A preferred palladium catalyst forthis process is a palladium(0) catalyst. A particularly preferredpalladium catalyst for this process is Pd₂(dba)₃.

In addition, the process is preferably performed in the presence of anadditive. Examples of preferred additives include monodentatephosphorus-containing ligands of formulas P(R_(C))₃ (phosphines) andP(OR_(D))₃ (phosphites), wherein each R_(C) is independently hydrogen;alkyl such as methyl, ethyl, and tert-butyl; cycloalkyl such ascyclopropyl and cyclohexyl; optionally substituted aryl, such as phenyl,naphthyl, and ortho-tolyl; and optionally substituted heteroaryl such asfuryl and pyridyl; and wherein each R_(D) is independently alkyl such asmethyl, ethyl, and tert-butyl; cycloalkyl, such as cyclopropyl andcyclohexyl; optionally substituted aryl, such as phenyl, naphthyl, andortho-tolyl; and optionally substituted heteroaryl, such as furyl andpyridyl. Specific examples of additives include, but are not limited to,tri(alkyl)phosphines such as trimethylphosphine, triethylphosphine,tributylphosphine, and the like; tri(cycloalkryl)phosphines such astricyclopropylphosphine, tricyclohexylphosphine, and the like;tri(aryl)phosphines such as triphenylphosphine, trinaphthylphosphine,and the like; tri(heteroaryl)phosphines such as tri(fury-2-yl)phosphine,tri(pyrid-3-yl)phosphine, and the like; tri(alkyl)phosphites such astrimethylphosphite, triethylphosphite, tributylphosphite, and the like;tri(cycloalkyl)-phosphites such as tricyelopropylphosphite,tricyclohexylphosphite, and the like; tri(aryl)phosphites such astriphenylphosphite, trinaphthylphosphite, and the like; andtri(heteroaryl)phosphites such as tri(fury-2-yl)phosphite,tri(pyrid-3-yl)phosphite, and the like. The term “additive,” as usedherein, also refers to bidentate phosphines such as1,4-bis(diphenylphosphino)butane (dppb),1,2-bis(diphenyl-phosphino)ethane (dppe),1,1-bis(diphenylphosphino)methane (dppm),1,2-bis(dimethyl-phosphino)ethane (dmpe),1,1′-bis(diphenylphosphino)ferrocene (dppf), and the like. Aparticularly preferred additive of the instant process is1,4-bis(diphenylphosphino)butane (dppb).

The process is carried out in an aprotic solvent. Suitable aproticsolvents include, but are not limited to, tetrahydrofuran,N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone,hexamethylphosphoric triamide, 1,2-dimethoxyethane, methyl-tert-butylether, heptane, acetonitrile, isopropyl acetate and ethyl acetate.Preferred aprotic solvents are tetrahydrofuran or toluene.

The instant conversion is performed preferably at an elevatedtemperature between 30 and 100° C. A particularly preferred temperaturerange is between 55° C. and 85° C. A most preferred temperature rangefor the instant alkylation process is between 60° C. and 75° C.

The instant alkylation process is generally conducted until at least 50%completion, preferably at least about 70% completion, typically until atleast 95% completion. Generally, the reaction time will be less thanabout 12 hours. A preferred reaction time range for the presentalkylation process is less than about 8 hours. A most preferred reactiontime range for the present alkylation process is less than about 7hours.

A compound of formula (III-a), wherein R₁ and R_(p) are as previouslydefined, are converted to a compound of formula (IV-a), wherein R_(p) isas previously defined, via the process illustrated in Scheme 1, step B.The removal of the cladinose moiety may be achieved either by mild acidhydrolysis or by enzymatic hydrolysis, at a temperature range of between−10° C. and 80° C., for a time period of from 0.5 to 24 hours, to afforda compound of formula (IV-a). Representative acids include dilutehydrochloric acid, sulfuric acid, perchloric acid, chloroacetic acid,dichloroacetic acid or trifluoroacetic acid. Suitable solvents for thereaction include water, methanol, ethanol, isopropanol, butanol and thelike. In a preferred embodiment, the removal of the cladinose moiety isachieved by treatment with aqueous hydrochloric acid, for a period of 1to 2 hours, at a temperature between 50° C. and 70° C. In a mostpreferred embodiment, 1M aqueous hydrochloric acid is used at atemperature of about 60° C.

As illustrated in Scheme 2, Step A, conversion of a compound of formula(IV-a) to a compound of formula (V), may be achieved by treating theformer with a reducing agent. Reducing agents suitable for thisconversion include, but are not limited to, lithium aluminum hydride,titanium(III)chloride, borane, and various sulfides such as sodiumhydrogen sulfide and sodium nitrite. For a more detailed account ofoxime reduction reaction, see J. March in “Advanced Organic Chemistry”4^(th) ed., Wiley & Son, Inc, 1992. In a particularly preferredembodiment, a compound of formula (IV-a) is treated with a titanium(III)reducing agent (preferably titanium(III)chloride), under acidicconditions, typically in a protogenic organic solvent. Preferred acidsinclude, but are not limited to, acetic acid, formic acid, dilutehydrochloric acid, dilute phosphoric acid, dilute sulfuric acid, and thelike. A particularly preferred acid for the present conversion isaqueous hydrochloric acid. Protogenic organic solvents suitable in thispreferred embodiment include, but are not limited to, mixtures of waterand methanol, ethanol, isopropanol, or butanol. A particularly preferredprotogenic organic solvent for the present conversion is ethanol. Theconversion is carried out between 10° C. and 110° C. (preferably betweenabout 20° C. and 50° C.) and over a period of less than about 10 hours(preferably between 2 to 4 hours).

As illustrated in Scheme 2, Step B, compounds of formula (V) can beconverted to compounds of formula (VI) by treating the former with anacylating agent. In a preferred embodiment, the conversion is carriedout in an aprotic solvent. Acylating agents suitable for the instantconversion include, but are not limited to, acetyl chloride, aceticanhydride, benzoyl chloride, benzoic anhydride, and benzylchloroformate.

Aprotic solvents suitable for the present conversion aredichloromethane, chloroform, tetrahydrofuran, N-methylpyrrolidinone,dimethylsulfoxide, N,N-dimethylformamide, N,N -dimethylacetamide,hexamethylphosphoric triamide, a mixture thereof or a mixture of one ofthese solvents with ether, tetrahydrofuran, 1,2-dimethoxyethane,1,2-dichloroethane, acetonitrile, ethyl acetate, acetone, and the like.A preferred aprotic solvent of the present process is selected fromdichloromethane, chloroform, N,N-dimethylformamide, tetrahydrofuran,N-methylpyrrolidinone or mixtures thereof. A particularly preferredaprotic solvent is dichloromethane.

Scheme 3 illustrates the process converting a compound of formula (VI)into a compound of formula (VII) through treatment with a reagent orreagents capable of performing oxidative cleavage. Oxidative cleavagemay be performed by, for example, ozonolysis or by treatment with anoxidant followed by a cleaving reagent. Ozonolysis may be achieved bytreating the alkene of a compound of formula (VI) with ozone followed bydecomposition of the ozonide with the appropriate reducing agent.Suitable reducing agents for this process include, but are not limitedto, dimethyl sulfide, zinc, trivalent phosphorous compounds, sodiumsulfite, and the like. The reaction is typically carried out in an inertsolvent such as, but not limited to, methanol, ethanol, ethyl acetate,glacial acetic acid, chloroform, methylene chloride or hexanes ormixtures thereof, preferably methanol, preferably at about −78° to −20°C. Preferred reducing agents include, but are not limited to,triphenylphosphine, trimethyl phosphite, thiourea, and dimethyl sulfide,preferably triphenylphosphine. A more thorough discussion of ozonolysisand the conditions there for can be found in J. March “Advanced OrganicChemistry”4^(th) ed., Wiley & Son, Inc, 1992.

An alternative method for the preparation of a compound of formula (VII)involves dihydroxylation of a compound of formula (IV) by an oxidantfollowed by treatment with a cleaving reagent. The glycol is firstprepared by reacting alkene with an oxidant. Suitable oxidants for thepresent process include, but are not limited to, permanganate ion andosmium tetroxide. The process may utilize stochiometric amounts ofosmium tetroxide, or, if in the presence of an additional oxidant suchas hydrogen peroxide, tert-butyl hydroperoxide,N-methylmorpholine-N-oxide, or barium chlorate only catalytic amounts ofosmium tetroxide are necessary. Dihydroxylation reactions can be carriedout in a variety of solvents including: 1,4-dioxane, tetrahydrofuran,tert-butanol and diethyl ether, preferably at a temperature of between−15° C. and 15° C.

The resulting glycol can be cleaved by a variety of cleaving reagentsincluding, but not limited to, periodic acid, lead tetraacetate,manganesedioxide, potassium permanganate, sodium metaperiodate, andN-iodosuccinamide. Preferably the cleavage reagent is sodium periodate,the solvent is preferably a mixture of acetone, THF, ethanol, methanolor 1,4-dioxane and water at a temperature of between 0° to 80° C.

A compound of the formula (VII) may be prepared by oxidation of the3-position alcohol using an oxidizing agent or agents. Oxidizing agentssuitable in the present process are either Swern oxidation reagents(dimethyl sulfoxide and an electrophilic compound selected fromdicyclohexylcarbodiimide, acetic anhydride, trifluoroacetic anhydride,oxalyl chloride, or sulfur trioxide), Dess-Martin periodane, orCorey-Kim oxidation reagents. A preferred method of oxidation is the useof the Corey-Kim oxidation reagents N-chlorosuccinimide and dimethylsulfide. The reaction typically takes place in an aprotic solvent at atemperature of between about −78° to 25° C. The reaction time typicallyis less than 12 hours. A more thorough discussion of the state of theart regarding oxidation of secondary alcohols can be found in J. Marchin “Advanced Organic Chemistry” 4^(th) ed., Wiley & Son, Inc, 1992.

A compound of formula (VIII) represents a useful intermediate which canbe further functionalized in a variety of ways. Scheme 4 details aprocedure for the conversion of a compound of formula (VIIIinto an oximecompound of formula (IX-a), by first treating with hydroxylamine offormula (X) followed by deprotection of the 2′ hydroxyl. Oxime formationcan be accomplished under either acidic or basic conditions in a varietyof solvents. Representative acids include, but are not limited to,hydrochloric, camphorsulfonic acid, phosphoric, sulfuric,para-toluenesulfonic, and pyridinium p-toluene sulfonate. Likewise baseswhich are useful include, but are not limited to, triethylamine,pyridine, diisopropylethyl amine 1,5-lutidine, imidazole, and the like.Appropriate solvents include, but are not limited to, methanol, ethanol,water, tetrahydrofuran, 1,2-dimethoxyethane, and ethyl acetate.Preferably the reaction is run in ethanol using triethylamine as thebase. The reaction temperature is generally 0° C. to 50° C. and theduration of the reaction is less than 12 hours. The deprotection can beachieved by for example methanolysis.

Scheme 5 illustrates the synthesis of the side chain (X). As outlined inScheme 5, Step A, a compound of formula (X) is prepared by byhydrogenation or transfer hydrogenation of4-(hydroxymethyl)-2-nitrophenol with palladium catalyst in the presenceof an acid, preferably in a protogenic solvent, to provide a compound ofthe formula (XII). In a preferred embodiment of the instant reaction,the reaction temperature is between 20° C. and 60° C. In a particularlypreferred embodiment of the instant reaction, 10% Pd/C and ammoniumformate are used, and the protogenic solvent is methanol.

A compound of formula (XIII) is prepared, as illustrated in Step B ofScheme 5, by treating a compound of formula (XII) with cyanogen bromidethe presence of a protogenic solvent preferably ethanol or methanol.Preferably, the reaction is performed at room temperature to refluxconditions.

A compound of formula (XIV) is prepared, as illustrated in Step C ofScheme 5, by halogenating compound of formula (XIII) with a halogenatingagent. Halogenating agents suitable for the instant conversion include,but are not limited to, PBr₃, thionyl chloride, and the like. Thepresent reaction preferably takes place in an aprotic solvent, at atemperature between about 0° C. and 50° C., for a duration of less than24 hours. Most preferably the present conversion takes place inmethylene chloride, at room temperature, and for a duration of from 12to 18 hours.

A compound of formula (XI) is prepared, as illustrated in Step D ofScheme 5, by adding the compound of formula R₃R₄NOH to a compound offormula (XIV), where R₃ and R₄ are taken together with the nitrogen atomto form

wherein A and B wherein A and B are hydrogen or A and B taken togetherwith the carbons to which they are attached form a cyclic moietyselected from aryl, substituted aryl, heterocyclic, substitutedheterocyclic, alicyclic, or substituted alicyclic. Preferably A and Bare hydrogen or A and B taken together with the carbon atoms to whichthey are attached are phenyl. The present conversion preferably takesplace in the presence of a base in an aprotic solvent.

A compound of formula (X) is prepared, as illustrated in Step E ofScheme 5, by hydrolyzing the compound of formula (XI) with a base in aprotogenic organic solvent or an aqueous mixture thereof. Preferably thebase is either hydrazine or ammonia.

Alternatively compound of formula (X) can also be prepared as outlinedin Scheme 6. A compound of formula (XVI) is prepared, as illustrated inStep A of Scheme 6, by treating 2-amino-4-methylphenol with cyanogenbromide the presence of a protogenic solvent preferably ethanol ormethanol. Preferably, the reaction is performed at room temperature toreflux conditions.

The amino moiety of compound (XVI) can be protected with a suitableamino protecting including but not limited to an acyl group orsuccinimide to furnish compound of the formula (XVI). Preferably, theprotecting group is succinimide. The present conversion preferably takesplace with succinic anhydride in the presence of an alkylating reagentsuch as HATU and a base such as N-methylmorpholine. Preferably, thereaction is performed at room temperature to reflux conditions.

A compound of formula (XVIII) is prepared, as illustrated in Step C ofscheme 6 with standard bromination conditions that are well known in theart of chemistry. Preferably, compound (XVII) is treated with NBS in thepresence of benzoyl peroxide in an aprotic solvent such as carbontetrachloride. Preferably, the reaction is performed at room temperatureto reflux conditions.

A compound of formula (XV) is prepared, as illustrated in Step D ofScheme 6, by adding the compound of formula R₃R₄NOH to a compound offormula (XVIII), where R₃ and R₄ are taken together with the nitrogenatom to form

wherein A and B wherein A and B are hydrogen or A and B taken togetherwith the carbons to which they are attached form a cyclic moietyselected from aryl, substituted aryl, heterocyclic, substitutedheterocyclic, alicyclic, or substituted alicyclic. Preferably A and Bare hydrogen or A and B taken together with the carbon atoms to whichthey are attached are phenyl. The present conversion preferably takesplace in the presence of a base in an aprotic solvent.

A compound of formula (X) is prepared, as illustrated in Step E ofScheme 6, by hydrolyzing the compound of formula (XV) with a base in aprotogenic organic solvent or an aqueous mixture thereof. Preferably,the base is either hydrazine or methylamine.

All references cited herein, whether in print, electronic, computerreadable storage media or other form, are expressly incorporated byreference in their entirety, including but not limited to, abstracts,articles, journals, publications, texts, treatises, internet web sites,databases, patents, and patent publications.

EXAMPLES

The compounds and processes of the present invention will be betterunderstood in connection with the following examples, which are intendedas an illustration only and not limiting of the scope of the invention.Various changes and modifications to the disclosed embodiments will beapparent to those skilled in the art and such changes and modificationsincluding, without limitation, those relating to the chemicalstructures, substituents, derivatives, formulations and/or methods ofthe invention may be made without departing from the spirit of theinvention and the scope of the appended claims.

Example 1 Preparation of O-Bis(Boc)-2-Methylene-1,3-Propanediol(Compound of Formula II wherein R₁₁ is Hydrogen and R₁ is Tert-butyl)

To a solution of di-tert-butyl dicarbonate (6.6 kg) in methylenechloride (15.0 L, 15 volumes) was added 2-methylene-1,3-propanediol(1.00 kg) and phase transfer catalyst tetrabutylammonium hydrogensulfate(0.641 kg). The resulting reaction mixture was then agitated vigorouslyat about 15° C. while adding over a 2 hr period, 6M aqueous sodiumhydroxide solution (13.2 L) and controlling the temperature between 25to 30° C. The resulting two-phase reaction mixture was subsequentlyagitated for a period of 2-3 hrs at 25° C.

The aqueous layer was discarded and additional phase transfer catalysttetrabutylammonium hydrogensulfate (0.064 kg, 10% of the initialamount), di-tert-butyl dicarbonate (0.66 kg, 10% of the initial amount),and methylene chloride (2.0 L, 2 volumes) was added to the remainingorganic reaction mixture. To the reaction mixture was also added 6Maqueous sodium hydroxide solution (1.32 L, 10% of the initial amount)over a period of about 0.5 to 1 hr, while controlling the temperaturebetween 25 to 30° C. The resulting two-phase reaction mixture was thenagitated at about 25° C. for additional 3 to 4 hr. Allowing more than 3hrs of agitation time is often required to complete the hydrolysis ofthe excess di-tert-butyl dicarbonate. The aqueous layer was discarded.The resulting organic phase was washed with water (3×8.0 L), dilutedwith EtOAc (6 L, 6 volumes), and distilled to an oil foam withquantitative yield.

¹H (500 MHz, CDCl₃) δ 5.15, 4.98, 4.79, 4.68, 4.68, 4.33, 4.31, 3.89,3.77, 3.67, 3.45, 3.35, 3.19, 2.88, 2.78, 2.74, 2.42, 2.17, 2.11, 2.06,1.95, 1.72, 1.66, 1.51, 1.48, 1.43, 1.34, 1.27, 1.19, 1.19, 1.18, 1.14,1.13, 1.11, 0.95, 0.85.

Example 2 Preparation of Erythromycin A 9-oxime 9,2′,4″-triacetate(Compound of Formula (I-c))

To a solution of erythromycin A oxime (1.0 kg) in EtOAc (4 L, 4 volumes)was added TEA (0.744 L) and DMAP (48.9 g). While agitating andmaintaining a temperature of less than 40° C., to the resulting reactionmixture was added acetic anhydride (0.441 L) over a period of 1-5 hrs.The reaction mixture was then agitated for an additional 1-5 hr periodat about 25° C. Additional TEA (0.0744 L, 10% of initial amount) wasthen added to the reaction mixture, and subsequently additional aceticanhydride (0.0441 L, 10% of initial amount) was added over the course of30 min while maintaining a temperature of less than 35° C. This mixturewas then further agitated for 1.5-2 hr at about 25° C. After thereaction had gone to completion, the reaction mixture was diluted withEtOAc (6 volumes), quenched with aqueous NaHCO₃ solution 3.0 L (3volumes), and agitated for 5-10 min at about 25° C. The aqueous phasewas then discarded. The remaining organic mixture was washed withaqueous NaHCO₃ solution (3.0 L, 3 volumes) and 15% aqueous brine (3.0 L,3 volumes), and concentrated in vacuo. The concentrated solution wasthen taken up in acetonitrile (4.0 L, 4 volumes) and concentrated invacuo two times until crystallization occurs. Upon formation ofcrystals, the slurry was agitated at 10° C. to 15° C. for at least 2 hrand the crystals were collected and dried under vacuum to afford whitecrystalline product with a typical yield of 70-80%.

¹H (500 MHz, CDCl₃) δ 5.15, 4.98, 4.79, 4.68, 4.68, 4.33, 4.31, 3.89,3.77, 3.67, 3.45, 3.35, 3.19, 2.88, 2.78, 2.74, 2.42, 2.17, 2.11, 2.06,1.95, 1.72, 1.66, 1.51, 1.48, 1.43, 1.34, 1.27, 1.19, 1.19, 1.18, 1.14,1.13, 1.11, 0.95, 0.85 ¹³C (125 MHz, CDCl₃) δ 178.7, 175.4, 170.4,170.0, 168.3, 100.6, 96.3, 83.4, 79.4, 79.0, 77.4, 74.9, 74.0, 72.6,72.2, 70.1, 67.7, 63.6, 63.4, 49.5, 45.0, 40.7, 39.2, 37.4, 35.7, 34.5,31.5, 28.6, 26.8, 21.8, 21.7, 21.5, 21.3, 21.1, 20.0, 18.7, 18.4, 16.7,16.1, 14.9, 10.9, 9.2.

Example 3 Preparation of 6,11-O,O-Bridged Erythromycin A 9-Oxime9,2′,4″-triacetate (Compound of Formula (III-c))

To a solution of the title compound of Example 2 (1.00 kg) in anhydrousTHF (5.0 L, 5 volumes) was added a solution of the title compound ofExample 1 (0.62 kg) in anhydrous THF (2.0 L, 2 volumes) while agitating.The resulting reaction mixture was subsequently degassed twice byapplication under reduced pressure and placed under nitrogen. To thedegassed reaction mixture was added 1,4-bis(diphenylphosphino)butane(dppb) (19.5 g), and tris(dibenzylideneacetone)dipalladium(0)[Pd₂(dba)₃] (20.8 g), after which the resulting reaction mixture wasimmediately degassed twice as previously described.

The degassed reaction mixture was then heated, while being agitated, toreflux [typically, reflux begins at about 65° C.] over the period ofabout 1 to 2 hrs and then held at a temperature of 67° C. to 69° C.,while being agitated, for a period of 6 hr. After the 6 hr period, thereaction mixture was allowed to cool to about 25° C. over the period of2 to 3 hrs and the reaction mixture was analyzed for completion by HPLC.

Once it had been determined that the reaction had gone to completion,the reaction was then filtered through a short pad (about 2 inchesthick) of silica gel 0.25-0.5 kg to remove the palladium catalyst,phosphine ligand, and other polar impurities. The reaction vessel wasthen rinsed with reagent-grade THF (2.0 L, 2 volumes), agitate/wash for10 min, and filtered through the short pad of silica gel, combining withfiltrate from the reaction mixture. The combined filtrate was thenconcentrated in vacuo to afford the title compound in THF solution. Thefinal remaining volume of the THF solution of the title compound wasapproximately 2-3 L (2-3 volumes) and was used directly in the followingstep without isolation.

Example 4 Preparation of 3-Decladinose-6,11-O,O-Bridged Erythromycin A9-Oxime (Compound of Formula (IV-c))

To the concentrated solution of the title compound of Example 3 wasadded 1M hydrochloric acid solution in water (8.0 L, 8 volumes). Theresulting reaction mixture was subsequently agitated and heated to 60°C. over a period of 1-2 hr and then held at said temperature for anadditional 2 hr.

After the reaction had gone to completion (determined by HPLC), thereaction mixture was cooled to about 25° C. over the period of about 3hrs. The aqueous reaction mixture was then washed with methyl tert-butylether (MTBE) (4.0 L×2, 4 volumes×2) while agitating at 25° C. for 10min, keeping the aqueous layer. To the aqueous reaction mixture was thenadded saturated aqueous K₂CO3 solution (about 0.8 kg of solid potassiumcarbonate in water) at 20 to 30° C. over the period of 1 to 2 hrs untilthe mixture is pH 9.5.

The resulting aqueous reaction mixture was then extracted EtOAc (4.0L×2, 4 volumes×2) while agitating at 25° C. for 10 min, keeping theupper organic layer. The combined organic phase was then washed withwater (4.0 L, 4 volumes) and subsequently concentrated in vacuo to avolume of 2-2.5 L. To the concentrated solution was added acetonitrile(4.0 L, 4 volumes) and concentrated in vacuo again until about 2 to 2.5L (2 to 2.5 volumes) remained. Once again, to the concentrated solutionwas added acetonitrile (2.0 L, 2 volumes) and concentrate in vacuo untilless than 2 L (<2 volumes) remains.

The concentrated solution was removed from reduced pressure and agitatedthe at 45° C. until crystallization began. The resulting slurry was thencooled to a temperature of 0-5° C. over a period of 4-5 hr and held atsaid temperature for an additional 2 hrs prior to collecting, washing,and drying the crystalline form of the title compound. The typical yieldfor this two-step one pot process (Pd-catalyzed bridge formation andsugar cleavage) is 40-45%.

¹H (500 MHz, CDCl₃) δ 5.09, 4.98, 4.97, 4.78, 4.74, 4.43, 4.39, 4.07,3.90, 3.84, 3.74, 3.67, 3.50, 3.43, 2.82, 2.79, 2.73, 2.62, 2.43, 2.31,2.08, 2.03, 1.77, 1.59, 1.46, 1.38, 1.35, 1.32, 1.24, 1.23, 1.22, 1.22,0.97, 0.97, 0.89 ¹³C (125 MHz, CDCl₃) δ 175.3, 170.2, 166.5, 143.7,119.2, 99.7, 82.3, 79.5, 78.2, 78.1, 77.6, 77.3, 77.0, 76.1, 74.0, 71.7,69.0, 65.6, 63.4, 43.9, 40.9, 37.5, 36.0, 34.3, 31.2, 25.7, 23.4, 21.7,21.4, 20.0, 19.6, 17.11, 15.7, 14.8, 12.0, 7.9.

Example 5 Preparation of 3-Decladinose-6,11-O,O-Bridged Erythromycin A9-Imine Acetamide 2′-Acetate (Compound of Formula (VI-b))

Step 5a. Preparation of 3-Decladinose-6,11-O,O-Bridzed Erythromycin A9-Imine Acetamide 2′-Acetate (Compound of Formula (V))

To an agitating solution of the title compound of Example 4 (1.00 kg) inethanol (2 L, 2 volumes) was added 20% titanium (III) chloride solutionin aqueous 3% hydrochloric acid (2.847 kg or 2.33 L) over the period ofabout 1 hr via an addition funnel, while adjusting the addition rate tocontrol maintain the temperature between 25 to 35° C. After adding allof the titanium(III) chloride solution, the reaction mixture was thenagitated for an additional 3 hrs at a temperature between 25° C. and 30°C. until the reaction was completed (by HPLC). To the reaction mixturewas then added pre-chilled purified water (15 L, 15 volumes).

To the resulting aqueous reaction mixture was added a solution of sodiumhydroxide (50%, w/w, 0.466 L) over a period of 0.5-1 hr, while adjustingthe addition rate to maintain a temperature between 25 to 35° C., untilthe reaction mixture had reached a pH of between 6 to 7. The reactionmixture was then treated with saturated aqueous potassium carbonatesolution (0.666 L) at 25 to 35° C. over a period of 1 to 2 hrs until theresulting reaction mixture was pH 9 to 10.

The basic aqueous reaction mixture was then extracted five times withmethylene chloride (5.0 L×5, 5 volumes×5) and the combined organicextract is concentrated in vacuo until about 5 L remain. To theconcentrated reaction mixture was then added additional methylenechloride (5.0 L) and removed in vacuo to azeotropically remove wateruntil about 5 L remain. The resulting methylene chloride solution wasdirectly used in the subsequent step without isolation.

Step 5b. Preparation of the 9-Imine Acetate (Compound of Formula(VI-b)).

Acetic anhydride (0.30 kg) is added to the concentrated solution fromStep 5a and the resulting mixture was agitated at 25 to 30° C. for 1.5hrs. After the acetylation reaction had gone to completion as evidencedby HPLC, the reaction mixture was concentrated in vacuo untilapproximately 2 L remained in the vessel. The remaining solution wasthen diluted with EtOAc (4.0 L, 4 volumes) and concentrated in vacuountil about 3 L remain. An additional amount of EtOAc (4.0 L, 4 volumes)was added to the concentrate and the diluted solution was concentratedonce again in vacuo until crystallization began (about 1.5 L remaining).To the remaining slurry was added n-hexane (1.5 L, 1.5 volumes) whilemaintaining the temperature of the solution at about 45° C. After theaddition of n-hexanes was complete, cool the solution to 0 to 5° C. overthe period of about 3 hr and agitate the resulting slurry at thistemperature for at least 2 hr before filtration. The crystals were thenfiltered and washed with chilled (<5° C.) ethyl acetate/hexane (1:2)(0.3 L, 0.3 volume). The collected crystals of the title compound werethen dried under a vacuum at a temperature of about 40-45° C. until aconstant weight was observed. The typical yield for this two-step onepot process (reduction and acetylation) is 80-89%.

¹H (500 MHz, CDCl₃) δ 5.18, 4.93, 4.75, 4.74, 4.59, 4.52, 4.13, 1.08,3.74, 3.60, 3.48, 3.43, 2.84, 2.73, 2.72, 2.66, 2.55, 2.43, 2.26, 2.02,1.73, 1.69, 1.46, 1.39, 1.33, 1.31, 1.26, 1.23, 1.23, 1.23, 1.10, 0.97,0.91 ¹³C (125 MHz, CDCl₃) δ 184.9, 178.0, 174.9, 170.1, 142.1, 122.4,99.8, 81.6, 79.1, 78.2, 77.5, 77.3, 77.0, 76.3, 76.2, 73.8, 71.9, 69.1,65.9, 63.4, 43.8, 40.9, 40.0, 38.4, 36.3, 35.7, 31.1, 25.7, 23.3, 21.7,21.4, 20.0, 19.7, 17.2, 16.0, 14.7, 12.0, 7.9.

Example 6 Preparation of 6,11-O,O-Bridged Ketone Erythromycin A 9-ImineAcetamide 2′-Acetate 3-ketolide (Compound of Formula (VIII-b))

Step 6a. Preparation of 3-Descladinose-6,11-Bridged Ketone ErythromycinA 9-Imine Acetamide 2′-Acetate (Compound of Formula VII-b)

To a solution of compound from step 5b of example 5 (20 g) in 200 mL ofethyl acetate/MeOH (10:1) was added MeSO₃H (2 mL, 1.1 eq.). The mixturewas then cooled down to −55° C. and white suspension resulted. Themixture was subjected to 45 min. of O₃ from the ozone generator. A lightblue color was observed. The solution was passed through with O₂ for 15min. at −55° C. to remove any excess O₃. The resulting white suspensionwas quenched with dimethyl sulfide (2.68 mL, 1.3 eq.) and the reactionmixture was slowly warmed up to room temperature. At room temperature,the solution was homogenous. The mixture was quenched with saturatedaqueous sodium bicarbonate (120 mL), further agitated and the organiclayer was separated. The aqueous layer was further extracted with 60 mLethyl acetate. The combined organic extracts were washed with 60 mL ofbrine, dried (Na₂SO₄), filtered and rotavaped to dryness to afford 16.3g of an amorphous white solid (82%). MS(ESI): m/e 713.75 (M+H). ¹³C (125MHz, CDCl₃) δ 205.5, 184.2, 175.5, 175.2, 169.8, 99.6, 81.9, 80.3, 79.7,78.3, 77.6, 76.7, 75.8, 71.7, 69.3, 68.9, 63.2, 44.0, 40.9, 39.1, 38.5,36.3, 36.1, 30.9, 25.3, 22.9, 21.6, 21.4, 19.8, 19.3, 17.1, 15.6, 14.8,11.4, 7.9.

Step 6b. Corey-Kim Reaction to Prepare the Title Compound of Formula(VIII-b).

A solution of N-chlorosuccinimide (NCS) (0.197 kg) in methylene chloride(3.5 L, 3.5 volumes) was agitated and cooled to a temperature ofapproximately −15° C. To the cooled solution was added dimethyl sulfide(0.145 L) over a period of 30 min via an addition funnel whilecontrolling the reaction temperature to about −15° C. After maintaininga temperature of −15° C. for 15 min., the solution was further cooled toa temperature of approximately −20° C. and to this cooled solution wasadded the methylene chloride/toluene solution of the olefin cleavageintermediate solution prepared in Step 6a (1 Kg) while maintaining areaction temperature of approximately −20° C. The reaction mixture wasagitated for an additional 3 hrs at a temperature of approximately −20°C., after which triethylamine (TEA) (0.196 L) was gradually added over aperiod of about 30 min. During the addition of TEA, the reaction mixturewas maintained at −15° C. by controlling the rate of addition. Theresulting reaction mixture was then agitated at the temperature of −15°C. for an additional 1 hr, after which the reaction mixture was warmedto 10° C. and diluted with EtOAc (16 L, 16 volumes). The dilutedreaction mixture was then washed with saturated aqueous sodiumbicarbonate solution (5 L×2, 5 volumes) and half-saturated aqueoussodium chloride solution (5 L, 5 volumes). The remaining organicsolution was then concentrated in vacuo at a temperature range of 45° C.to 50° C. until 1.5 L remain. To the concentrated solution is addedethanol (2.5 L, 2.5 volumes) while continuing to concentrate the organicsolution in vacuo until crystallization begins. The concentratedsolution was then cooled gradually to a temperature of 0° C. for aperiod of at least 2 hrs. The crystalline title compound was thencollected, washed with chilled (about 0° C.) ethanol (0.15 L), and driedat 25° C. under reduced pressure. The typical yield for this two-stepone pot process (oxidative cleavage and Corey-Kim oxidation) is 55-60%.

¹H (500 MHz, CDCl₃) δ 4.93, 4.78, 4.63, 4.53, 4.41, 4.34, 4.24, 4.00,3.95, 3.65, 3.56, 3.44, 2.87, 2.83, 2.67, 2.64, 2.36, 2.08, 2.07, 1.84,1.79, 1.57, 1.49, 1.38, 1.35, 1.33, 1.32, 1.29, 1.28, 1.27, 1.17, 0.92¹³C (125 MHz, CDCl₃) δ 205.5, 205.2, 184.5, 175.8, 170.2, 169.7, 100.0,80.2, 79.0, 78.9, 77.6, 76.1, 75.8, 74.6, 71.6, 69.3, 68.7, 63.5, 58.4,51.0, 45.4, 40.8, 39.7, 38.7, 36.6, 30.8, 25.5, 23.1, 21.6, 21.2, 20.0,19.6, 18.6, 17.2, 15.5, 14.2, 13.0, 11.6

Example 7 Preparation of 1-(2-aminobenzofdloxazol-5-yl)-hydroxylamine(Compound of Formula (X))

Step 7a. Pd-C (10% weight, ˜130 g) was placed in a reactor under N₂. Asolution of compound 2 (1.32 Kg, 7.804 mol) in MeOH (16 L) was addedunder N₂. HCOONH₄ (2.6 Kg, 41.2 mol) was added in one portion. Thereaction mixture was stirred, and the reaction temperature initiallychanged from 17° C. to 12° C. then rose gradually up to 28° C. Thereaction temperature was controlled at 25-29° C. by setting the coolingjacket at 20° C. After 24 h, NMR indicated the reaction was completed.Nitrogen was bubbled into the reaction mixture to remove any remaininghydrogen. The mixture was filtered through celite, washed with MeOH (7L). The combined filtrates (25 L) were immediately concentrated invacuum to almost dryness, co-evaporated with MeOH (6 L) to almostdryness. The residue was used directly in next stage.

Step 7b. A mixture of the compound from Step 7a and anhydrous MeOH (14L) was placed in a reactor. Solid BrCN (0.937 Kg, 8.6 mol) was added(over 45 min) at such a rate that the internal temperature did no exceed30° C. The reaction mixture was stirred at room temperature for 14 h.HPLC indicated the completion of reaction. The mixture was concentratedin vacuum at 40° C. to a total volume about 13 L (4 L of methanol wasremoved). EtOAc (20 L) was added and followed by slow addition of anaqueous K₂CO₃ (w/w 20%, ca. 1 Kg in 4 L of water) at 14 to 20° C. Themixture's pH value is ca. 9. Water (7 L) was added, and the mixture wasstirred for 15 min (aqueous phase pH 9˜10). After extraction, theaqueous phase was further extracted with EtOAc (3×18 L). The combinedorganic layers were washed with half saturated aqueous NaCl (15 L) andconcentrated to almost dryness, co-evaporated with MeOH (8 L) to almostdryness. The residue was dissolved in hot MeOH (4 L) at 80° C. bath. Thesolution gradually cooled to room temperature (crystallization began),then to 0° C. over 3 h. The mixture was stirred at 0° C. for anadditional hour, filtered, washed with cold MeOH (100 ml). The collectedbeige solid (compound 3 was dried in vacuum at 40° C. for 27 h. Weight:0.706 Kg, HPLC 97.1%. The mother liquid was further crystallized toafford more of the desired compound (0.21 Kg).

MS(ESI): m/e 165.10 (M+H).

C¹³ (DMSO-d₆): 63.10, 107.59, 113.52, 118.36, 137.95, 143.45,146.81,162.86.

Step 7c. Compound from Step 7b (0.77 Kg, 4.69 mol) was placed in a dryreactor under N₂. Anhydrous DMF (4 L) was added and the resultingsolution was stirred and cooled to 0° C. by setting the cooling jacketat −10° C. Thionyl chloride (370 ml, 5.07 mol) was added slowly whilethe internal reaction temperature was controlled at 0 to 3° C. duringthe addition. After the addition was completed, the reaction mixture wasstirred at 0° C. for 3 h. HPLC indicated the reaction was completed (theproduct 93%). Added slowly 0.55 L of an aqueous K₂CO₃ (1.5 Kg in 10 L ofwater) while the temperature did not exceed 5° C. ETOAc (8 L) was added,followed by slow addition of the remaining portion of aqueous K₂CO3 (themixture's pH: 8) over 0.5 h. EtOAc (24 L) was added, the mixture wasstirred for 10-15 min. The separated lower aqueous phase (pH 8 to 9) wasfurther extracted with EtOAc (2×11 L). The combined organic layers werewashed with saturated aqueous NaHCO₃ (4×7 L) and half saturated aq. NaCl(7 L), concentrated in vacuo to almost dryness, co-evaporated with CH3CN(4 L) to dryness to afford the desired chlorinated product (0.739 Kg,86% yield, HPLC purity >95%), which is pure enough for next step. Purersample can be obtained by crystallization in acetonitrile.

MS(ESI): m/e 183.05 (M+H). C13 (DMSO-d6): 46.85, 108.20, 115.72, 120.95,133.03, 143.86, 147.78, 163.28.

Step 7d. To the compound from Step 7c (0.633 Kg, 3.46 mol) was addedCH₃CN (8 L). The mixture was stirred at 50° C for 1 h, insolubleimpurities were filtered off. The filtrate was added toN-hydroxysuccinimide (0.61 Kg, 5.3 mol) in a flask. The resultingsolution was cooled to 15° C., diisopropylethylamine (1.1 L, 6.2 mol)was added slowly over 15 min. The resulting mixture was stirred at 50°C. until HPLC indicated the completion of reaction (at least 6 h). Thereaction mixture was cooled to room temperature. The mixture was stirredat 0° C. for at least 2 h, filtered, washed with pre-chilled CH₃CN (250ml). The collected beige solid was further dried in vacuum at 40° C. for24 h to afford EP-014723 (0.711 Kg, 79% yield, HPLC purity >95%). Thematerial can be further purified by re-crystallization from MeOH to givethe sample with HPLC purity >99%.

MS(ESI): m/e 262.13 (M+H). C13 (DMSO-d6): 26.14, 78.99, 108.82, 117.26,122.49, 130.29, 144.49, 149.05, 163.96, 172.76.

Step 7e. Compound from Step 7d (0.821 Kg, 3.14 mol) was dissolved inmethanol (16.5 L, 20 volumes). To this solution was added a solution of33% wt MeNH₂ in ethanol (2.50 L, 6.3 eq.). The homogeneous mixture washeated to 64° C. for 5 hours and then it was cooled to room temperature.The excess solvents were rotavaped off to a quarter of its volume andthen it was recharged with 3 vols of methanol and then it was evaporatedto dryness. The resulting solid was vacuum dried at room temperatureovernight to give 0.980 Kg of the title compound which was directly usedin the next step without further purification.

Example 8 Preparation of Compound of Formula (IX-a)

Step 8a. Oxime Formation Step

To a −10° C. cooled solution of the1-(2-aminobenzo[d]oxazol-5-yl)-hydroxylamine (compound of formula (X))from Step 7e of Example 7 (3.14 mol, 1.18 eq.) in ethanol (5.35 L, 2.8volumes) was added 1.5 M aqueous hydrochloric acid (5.35 L, 2.8 volumes,3.0 eq.) while maintaining a temperature below 25° C. by controlling therate of addition. The resulting reaction mixture was then cooled to atemperature between 0 to 1° C. To the cooled reaction mixture was addedthe title compound of Example 6 (1.90 kg) while maintaining a reactiontemperature less than 1° C. After the addition had been completed, thereaction mixture was agitated for a period of 1 hr. The mixture waswarmed to 15° C. and the reaction mixture was subsequently diluted withEtOAc (10 volumes) and to this diluted reaction mixture was addedsaturated aqueous sodium bicarbonate solution (8.5 volumes) at atemperature below 25° C. until the pH of the mixture was between 8 and9. The biphasic solution was agitated at 23° C. for 10 min before theorganic layer was separated from the aqueous phase. The aqueous layerwas further extracted with additional EtOAc (5 volumes). The combinedorganic extracts were then washed with brine (6 volumes), dried(Na₂SO₄), filtered and then concentrated in vacuo until only a stickyoil residue remains. This residue was subsequent crystallized inmethanol (11 volumes to the diketone starting material Example 6) togive 1.9 Kg of the desired product as a wet cake (purity 91-93% byHPLC). MS(ESI): m/e 872.82 (M+H). ¹³C (125 MHz, CDCl₃) δ 205.6, 184.5,177.7, 169.8, 167.4, 162.2, 152.9, 148.2, 142.7, 133.7, 121.8, 116.8,108.6, 100.7, 79.3, 78.6, 76.5, 76.3, 74.8, 74.7, 71.7, 69.4, 63.7,63.3, 62.9, 50.9, 45.7, 40.9, 40.3, 38.7, 37.5, 30.9, 25.3, 23.7, 21.6,21.2, 20.3, 19.6, 17.8, 15.1, 13.9, 13.4, 13.0.

Step 8b. 2′ Deprotection

To the wet cake from Step 8a was added methanol (8.0 L) and theresulting mixture was rotated in a rotavap at 35° C. for approximately19 hours after which the deacetylation reaction was complete asevidenced by HPLC. The reaction mixture was then concentrated in vacuountil approximately 2.0 L remained. The suspension was cooled to 0° C.and held at that temperature for 30 min. The solid was filtered off andrinsed with cold methanol (50 mL). The mother liquor still contained 70%of the E isomer and 14% of the Z isomer. The solid was vacuum dried at30° C. overnight to give 0.915 Kg of the product. The residue was thendissolved with ethyl acetate (4.0 L, 4.5 volumes) in a 65-70° C. bath.To this solution was added slowly hexanes (6 L, 6.6 volumes) whilemaintaining a temperature of approximately 65° C. Fine crystals crashedout. The mixture was cooled to 20 C and held at that temperature for 2hours. The solid was filtered off and washed with ethyl acetate/hexanes.The wet solid was dried in a vacuum oven at 30 C for 3 hours and at 25°C. for 24 hours to give 0.735 Kg of the title compound. MS(ESI): m/e830.41 (M+H). ¹³C (125 MHz, CDCl₃) δ 205.6, 184.4, 177.5, 167.6, 162.2,153.1, 148.2, 142.7, 133.8, 121.8, 116.8, 108.6, 103.0, 79.3, 78.6,76.5, 76.3, 75.6, 74.7, 70.4, 69.7, 66.0, 63.1, 62.9, 50.7, 46.2, 40.5,40.3, 38.7, 37.2, 28.5, 25.3, 23.7, 21.5, 20.5, 19.6, 17.8, 15.1, 13.9,13.8, 12.7.

Example 9 Alternative Preparation ofO-(2-aminobenzo[d]oxazolyl-5-methyl)-hydroxylamine (Compound of Formula(X))

Step 9a. To a solution of 2-amino-4-methylphenol (2-amino-p-cresol, Mol.Wt.: 123.15, 157.6 g, 1.28 mol) in 1500 ml of EtOH at room temperature,under stirred condition, was added bromocyanogen (Mol. Wt.: 105.92,135.00 g, 1.28 mol) in about 30 mins. During the addition, the reactionmixture became to warm and water bath was used to cool the reaction toroom temperature. The reaction color became to a dark color. After 5-6hours, the reaction solvent was evaporated under reduced pressure. Theresidue was dissolved in about 1500 ml of EtOAc and washed with thesaturated 1500 ml NaHCO₃, the gas of CO₂ was generated, and water phasewas separated and washed again by 400 ml of EtOAc. The organic layer wascombined and dried over anhydrous MgSO₄. Removal of solvent and dried byhigh vacuum yielded about 150 g of product 2 as pale brown color, whichcan be used in next step. The TLC RF value of the product is about 0.35in solution of acetone and hexane by the ratio of 1 to 2. MS(ESI): m/e149 (M+H), 1H NMR (CDCl3) (ppm): 2.21 (s, 3H); 5.30 (bs, 2H); 6.99 (d,1H); 7.10 (s, 1H); 7.22 (d, 2H).

Step 9b. In 2500 ml of anhydrous toluene, succinic anhydride (Mol. Wt.:100.07, 141.1 g, 1.41 mol) and 70 g (about 0.47 mol) of compound fromStep 9a were added under stirred condition, and then the mixture wasrefluxed for overnight. After that, 100 g (0.26 mol) of HATU and 41.36ml (0.376 mol) of 4-methylpholine were added and then the resultingmixture was refluxed for 2-3 hours. TLC showed that the major spot wasproduct and its TLC RF value is about 0.45 in solution of acetone andhexane by the ratio of 1 to 2. After reaction was completed, the solventwas evaporated and the residues was dissolved in about 2000 ml ofCH₂Cl₂, the solution was treated with aqueous NaHCO₃ and CO₂ wasgenerated during stirring. After pH was adjusted to be about 7-8 andwashed with brine, organic phase was separated and dried over MgSO₄.Filtration and removal of solvent gave about 98 g of crude desiredproduct as fine white needle crystalline. MS(ESI): m/e (M+H) 231.

Step 9c. To the 1.5 L of CCl₄ under stirring condition, 44.37 g (about0.193 mol) of compound from Step 9b and 41.16 g (about 0.23 mol) of NBSwas added and then the mixture were heated to reflux. 0.15 g of Benzoylperoxide was added by three times. This suspension mixture became tosolution after 17 hours refluxing, and the solid was found on the flaskinside. The color of the reaction solution became to red and then turnedto yellow. Other of 0.15 g of Benzoyl peroxide was added again after 6hours. TLC was used to monitor reaction every two-three hours, and theproduct's RF value was about 0.4 in solution of acetone and hexane bythe ratio of 1 to 2. After completion, the reaction was cooled to roomtemperature and the white solid was formed. The mixture was diluted with1.5 L of CH₂Cl₂ until the white solid was disappearing and organic phasewas washed with 4 L of saturated NaHCO₃ two times to adjusted pH 7-8,dried over MgSO₄, filtrated, and removal of the solvent under reducedpressure, dried by high vacuum gave about 57.3 g of the desired productas slight yellow solid. HPLC test at 254 nm indicated that this productwas about 77.6% purity. This product can be used for next step withoutfurther purification. MS(ESI): m/e (M+H) 309, 311.

Step 9d. To 450 ml of MeCN, 57.3 g (about 0.185 mol) of the compoundfrom Step C was added and heated to about 50° C., under stirringcondition 60.51 g (0.371 mol) N-hydroxyphanthalimide and 80 ml oftriethylamine were added. The reaction mixture became to deep red colorand the solid product was formed after 10-15 mins. The reaction mixturewas stirred at room temperature for further 8 hours. After filtration,the pale yellow product was collected, which was washed by 100 ml ofMeOH and ether in the 1:1 ratio. After drying by vacuum, about 48 g ofthe desired product was obtained as pale solid, its HPLC at 254 nm gavethe single peak, which is less polar than starting material from Step 9cand TLC showed single spot at about 0.4 RF value in solution of acetoneand hexane by the ratio of 1 to 2. MS(ESI): m/e 392.

Step 9e. A solution of the compound from Setp 9d (3.91 g, 10 mmol) in100 ml 2M ammonia in methanol was stirred at 40° C. for 16 hours. Thereaction mixture was filtered and the filtrate was concentrated. Theresidue was purified on silica gel column (CH₂Cl₂/MeOH˜10/1) to give thetitle compound (1.7 g, 95%).

MS(ESI): m/e 180 (M+H).

Although the invention has been described in detail with respect tovarious preferred embodiments it is not intended to be limited thereto,but rather those skilled in the art will recognize that variations andmodifications may be made therein which are within the spirit of theinvention and the scope of the appended claims.

1. A process for preparing a compound of formula (XI):

Wherein R₃ and R₄ are hydrogen; or one of R₃ or R₄ is a hydrogen and theother is selected from: (a) C(O)R₅, where R₅ is C₁-C₆ alkyl, optionallysubstituted with one or more substituents selected from aryl,substituted aryl, heteroaryl, or substituted heteroaryl; (b) C(O)OR₅,where R₅ is as previously defined; or R₃ and R₄ are taken together withthe nitrogen atom to which they are attached to form

wherein A and B are each independently hydrogen, a substituted orunsubstituted aliphatic group, a substituted or unsubstituted cyclicgroup, a substituted or unsubstituted heterocyclic group, a substitutedor unsubstituted aryl group, a substituted or unsubstituted alicyclicgroup, or a substituted or unsubstituted heteroaryl group; or A and Btaken together with the carbon to which they are attached form a cyclicmoiety selected from: aryl, substituted aryl, heterocyclic, substitutedheterocyclic, alicyclic, or substituted alicyclic; alternatively, R₃ andR₄ are taken together with the nitrogen atom to which they are attachedto form N═C(R₆)(R₇), where R₆ and R₇ are each independently selectedfrom a substituted or unsubstituted aliphatic group, a substituted orunsubstituted cyclic group, a substituted or unsubstituted heterocyclicgroup, a substituted or unsubstituted aryl group, a substituted orunsubstituted alicyclic group, or a substituted or unsubstitutedheteroaryl group; said process comprising: (1) reducing4-(hydroxymethyl)-2-nitrophenol with a reducing agent to providecompound of formula (XII):

(2) reacting cyanogen bromide with compound of formula (XII) in asolvent to give compound of formula (XIII):

(3) halogenating the resulting compound with a chlorinating reagent toprovide a compound of formula (XIV);

(4) treating compound of formula (XIV) with a compound of formulaR₃R₄NOH in the presence of base to yield a compound of formula (XI). 2.The Process of claim 1 further comprising the step of hydrolyzing thecompound of formula XI with a base or an acid in a protogenic organicsolvent or aqueous solution, to yield a compound of formula (X):


3. The process of claim 1, wherein step 1 comprises hydrogenating4-(hydroxymethyl)-2-nitrophenol with palladium on carbon in the presenceof hydrogen gas to provide 2-amino-4-(hydroxymethyl)phenol.
 4. Theprocess of claim 1, wherein step 2 comprises treating2-amino-4-(hydroxymethyl)phenol with cyanogenbromide in methanol toprovide (2-aminobenzo[d]oxazol-5-yl)methanol.
 5. The process of claim 1,wherein step 3 comprises reacting thionyl chloride with(2-aminobenzo[d]oxazol-5-yl)methanol to provide5-(chloromethyl)benzo[d]oxazol-2-amine.
 6. The process of claim 1,wherein step 4 comprises reacting N-hydroxysuccinimide with5-(chloromethyl)benzo[d]oxazol-2-amine in the presence ofdiisopropylethylamine to provide1-((2-aminobenzo[d]oxazol-5-yl)methoxy)pyrrolidine-2,5-dione.
 7. Theprocess of claim 1, wherein step 4 comprises reactingN-hydroxysuccinimide with 5-(chloromethyl)benzo[d]oxazol-2-amine in thepresence of DBU to provide1-((2-aminobenzo[d]oxazol-5-yl)methoxy)pyrrolidine-2,5-dione.
 8. Theprocess of claim 2 comprising reacting methylamine with1-((2-aminobenzo[d]oxazol-5-yl)methoxy)pyrrolidine-2,5-dione in methanolto provide O-(2-aminobenzo[d]oxazol-5-yl)methyl hydroxylamine.
 9. Theprocess of claim 2 further comprising the step of adding the compound offormula X to the compound of formula (VIII-a):

with an acid in a protogenic organic solvent or aqueous solution, toyield a compound of formula (IX-b):


10. The Process of claim 9 further comprising the step of deprotectingthe compound of formula (IX-b) with a protogenic organic solvent oraqueous solution, to yield a compound of formula (IX-a):